Hi Peter, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on vhost/linux-next] [also build test WARNING on linus/master v5.7-rc7] [cannot apply to kvm/linux-next tip/auto-latest linux/master next-20200526] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982] url: https://github.com/0day-ci/linux/commits/Peter-Xu/KVM-Dirty-ring-interface/20200524-070926 base: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next config: i386-randconfig-s002-20200527 (attached as .config) compiler: gcc-9 (Debian 9.3.0-13) 9.3.0 reproduce: # apt-get install sparse # sparse version: v0.6.1-240-gf0fe1cd9-dirty # save the attached .config to linux build tree make W=1 C=1 ARCH=i386 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot sparse warnings: (new ones prefixed by >>) arch/x86/kvm/mmu/mmu.c:693:18: sparse: sparse: cast to non-scalar arch/x86/kvm/mmu/mmu.c:712:18: sparse: sparse: cast to non-scalar arch/x86/kvm/mmu/mmu.c:731:18: sparse: sparse: cast to non-scalar >> arch/x86/kvm/mmu/mmu.c:1280:24: sparse: sparse: Using plain integer as NULL pointer arch/x86/kvm/mmu/mmu.c:4687:57: sparse: sparse: cast truncates bits from constant value (ffffff33 becomes 33) arch/x86/kvm/mmu/mmu.c:4689:56: sparse: sparse: cast truncates bits from constant value (ffffff0f becomes f) arch/x86/kvm/mmu/mmu.c:4691:57: sparse: sparse: cast truncates bits from constant value (ffffff55 becomes 55) vim +1280 arch/x86/kvm/mmu/mmu.c 1269 1270 static struct kvm_memory_slot * 1271 gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn, 1272 bool no_dirty_log) 1273 { 1274 struct kvm_memory_slot *slot; 1275 1276 slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); 1277 if (!slot || slot->flags & KVM_MEMSLOT_INVALID) 1278 return NULL; 1279 if (no_dirty_log && kvm_slot_dirty_track_enabled(slot)) > 1280 return false; 1281 1282 return slot; 1283 } 1284 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org